Munchies:The key to writing a good sex scene: vanilla or otherwise, is transporting the reader into the scene. Not as if they are spectators but rather active participants.
Here are some articles that helped me when I started writing sex scenes ages ago:
dianagabaldon.com/2012/07/how-to-write-sex-scenes/dianagabaldon.com/2012/07/how-to-write-sex-scenes/dianagabaldon.com/2012/07/how-to-write-sex-scenes/Another important element of a good sex scene is character design and the choreography. Just as artists and animators have references or act out certain scenes, writers can do the same. It brings cohesion to your work and can make some aspects of writing easier.
I see many stories here that describe characters in ways that don't make any sense. For example, a writer might describe a woman as "fat and busty" when she is 5'6", 130 lbs, and a B cup. That will ruin the immersion for anyone who knows what such a woman would look like.
I found this site ages ago, and it really helps figure things out:
dianagabaldon.com/2012/07/how-to-write-sex-scenes/You can select a gender, height, and weight to find tons of matches. Just flick through the photos until you find the body shape you're looking at.
In terms of scene choreography, there are many different techniques. You can act things out alone, with a partner, or make rough sketches. Hell, even crude stick figures will do. Don't be afraid to make notes or reread previous scenes so you can keep relevant details in mind.
Letters And Numbers:Those links are all great and well worth reading for any authors out there!
I may make a separate thread with free/low cost resources when I have the time.